Heretofore, in an intake passage of an internal combustion engine, for example, a flap valve (a butterfly valve) is provided in order to change over the intake pipe length and regulate the flow of intake air (swirling flow, tumbling flow), and so on. This flap valve is fixed to the shaft. The shaft is rotatably supported by a bearing. When this shaft is rotated, the flap valve is also rotated.
Meanwhile, regarding a technique of supporting a shaft of a flap valve, for example JP2005-315258A discloses a flap valve device configured such that separate bearing members are mounted respectively in a plurality of divided passages of an intake passage in an internal combustion engine, and flap valves are supported by those bearing members. In this device, the shaft of each flap valve is covered in an angular range wider than 180° by the bearing members. Accordingly, each bearing part has a simple structure and a mounting operation is facilitated.